[squash] return an error on StatsFS

Author: mauriciopoppe

Diff for: pkg/mount-manager/statter_windows.go

@@ -48,17 +48,13 @@ func (r *realStatter) StatFS(path string) (available, capacity, used, inodesFree
 		return r.StatFSV1Beta(path)
 	}
 
-	return 1, 1, 1, 1, 1, 1, nil
+	return 1, 1, 1, 1, 1, 1, fmt.Errorf("Invalid interface type=%v", r.mounter.Interface)
 }
 
 func (r *realStatter) StatFSV1(path string) (available, capacity, used, inodesFree, inodes, inodesUsed int64, err error) {
 	zero := int64(0)
 
-	proxy, ok := r.mounter.Interface.(*CSIProxyMounterV1)
-	if !ok {
-		return zero, zero, zero, zero, zero, zero, fmt.Errorf("could not cast to csi proxy class")
-	}
-
+	proxy := r.mounter.Interface.(*CSIProxyMounterV1)
 	idRequest := &volumeapiv1.VolumeIDFromMountRequest{
 		Mount: path,
 	}
@@ -84,10 +80,7 @@ func (r *realStatter) StatFSV1(path string) (available, capacity, used, inodesFr
 func (r *realStatter) StatFSV1Beta(path string) (available, capacity, used, inodesFree, inodes, inodesUsed int64, err error) {
 	zero := int64(0)
 
-	proxy, ok := r.mounter.Interface.(*CSIProxyMounterV1Beta)
-	if !ok {
-		return zero, zero, zero, zero, zero, zero, fmt.Errorf("could not cast to csi proxy class")
-	}
+	proxy := r.mounter.Interface.(*CSIProxyMounterV1Beta)
 
 	idRequest := &volumeapiv1beta1.VolumeIDFromMountRequest{
 		Mount: path,